Troubleshooting Chip-Out with Melamine

Blade characteristics and plunge depth are factors to consider. February 18, 2011

I have a Holtzer Model 1250 panel saw and am experiencing a lot of chip-out, front and back. Of course I have changed the scoring knives and the blade I have in now only has about 20 sheet of 3/4" melamine under its belt (new blade). I had the tech in to the tune of $550 and all was well for a while, then the chipping started again. He says it's probably the melamine, but I use Duramine and I'm told it is one of the best. Is anyone else experiencing similar problems with their Holtzer machine?

Forum Responses
(Cabinetmaking Forum)
From contributor T:
It might be the melamine, but it might not. I say that because we use the same board and usually it's pretty good. Our last two units seemed to fall short in quality. We had more chipping than we had seen before and even had melamine pop off the board in some cases. I've been meaning to call in their rep about it.

On the other hand, what type of blade are you cutting with? The best (we've found) is of course, hollow ground, but only when new. After you have them sharpened, forget it. We settled on triple chip with (I believe) a slight negative hook angle. We get some chips, but not too bad, and not much different after sharpening. The other thing to check is your plunge depth. It affects the angle of attack on the board. Also, sometimes less pressure on the knives is better than more pressure. Another comment (depending on the tech you got), double check that your column and grid are parallel, and that your board it consistently tight to the grid. If not, check the bottom board (if your machine is like ours) that is supposed to be in line with the grid, just above the bottom shelf. Ours was spaced out slightly with a shim behind it. We had to pull it out and remove the shim so our board would lay flat to the grid. All that said, from our experience, 20 sheets fully processed probably isn't bad. I know it depends on the sizes but that might a lot of lineal feet of cutting on that blade. I can't remember if we get more or less between blade changes.

From the original questioner:
That helps to settle my mind a little. I did receive a phone call from the Holzher sales rep. and he was very concerned. Something you don't see too often any more. He recommended I call back my service tech. and have him go over the machine again. If I don't get any satisfaction from that then I'm to call him back and he'll make other arrangements.

Anyway, to answer your questions, I use a triple chip blade, designed for melamine. Additionally, I have about 2mm of "plunge" with the scoring knives, which I think is recommended. I'll change the blade and see what's going on there. It's unfortunate that they aren't very good when sharpened at about $80 a shot new - that does tend to raise the cost of doing business. I guess I better pay more attention to cost factors like this when preparing my bids.

From contributor P:

2mm is a very deep cut with the scoring knives - my manual wants them set only deep enough to cut through the melamine layer, virtually a scratch. Check your blade alignment - if the blade doesn't sit dead-parallel to the axis of travel, the rising teeth could be causing chipping on the underside of the panel.

From the original questioner:
I may have misrepresented my meaning when I said a 2mm depth of cut, and please correct me if I'm still wrong. I set the knives on the panel, with no tension then reset the scale to a +2mm beyond the thickness of the panel. Then when I reset the knives to the actual thickness of the panel there is about 2mm worth of pressure on the knives. I don't believe the knives are actually penetrating the panel a full 2mm - pretty much a surface scratch. None the less, I feel a difference in resistance when the knives go past the end of the panel during a cut.

Do you have preference in blade manufacturer, number of teeth, and type of blade? By the way, I did make a mistake in my initial question. The saw model is 1265S vs 1250, not sure where that number came from.

From contributor P:
On my 1265S I used Amana blades, a triple-chip and their high-ATB. Both worked fine. Thanks for clarifying on your scoring depth - I was having trouble imagining the down-pressure you'd need to carve a 2mm trough with fixed knives! Take a minute to understand and fine-tune the adjustment system on the scorer. It should be just a hair wider than your kerf.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
We have been using triple chip blades to cut melamine for about 20 years. When we have chip out it's either the blade is dull, the scoring blade is dull or set too narrow, or the panel is shifting slightly when being cut. We have an excellent blade man and our blades cut well all the time. You might check around for other sharpening people. There is a huge difference between and person passionate about sharp and one who is just sharpening.